Empirical radiometric correction of a silicon photodiode rotating shadowband pyranometer

Abstract We have improved the silicon photodiode-based rotating shadowband pyranometer[1] to suit it for radiometric observations by deriving empirical corrections to mimic thermopile sensors. We present the results of an intercomparison between our rotating shadowband pyranometer and a conventional complement of first-class thermopile instruments. The daily integrated values for total horizontal, diffuse horizontal and direct normal irradiance measured with our rotating shadowband radiometer agree on average to better than 1%, 3%, and 2.5%, respectively, with the thermopile results, after our empirically derived corrections are applied. In absolute units, 10-minute integrated values seldom differ by more than 20 watts/m 2 from the thermopile values.